This study is part of a 15-year project to develop less invasive methods to diagnose pneumocystis pneumonia and to predict responses to therapy. Oral washes, induced sputum, and bronchalveolar lavage have been collected from patients with immunosuppressive diseases and respiratory syndromes. During this trial resulting studies have moved the field from a focus on tissue to a focus on respiratory secretions, especially secretions that can be obtained non-invasively. Oral washes have been collected prospectively from patients at San Francisco General Hospital who have HIV infection and possible pneumocystis pneumonia. Quantitative PCR had a high sensitivity and high specificity for identifying patients with pneumocystis penumonia, especially if a cut-off of 50 copies/uL were used. This sutdy is completed. Further studies using improved methods to solubulize the clinical specimen are underway.